COVER CROP PRODUCTION FOR SEVERAL PLANTING AND HARVEST DATES IN EASTERN NEBRASKA

Species used for cover crops vary greatly in their growth response to water availability, soil temperature, length of growing period, day le ngth, and related environmental factors. Few reports compare growth of different species at different times during the growing season. This 4-yr field experiment at Lincoln, NE, compared growth of some 20 speci es as affected by planting date and length of the growth period. All s pecies were planted as early as possible each spring, with a second se eding in early summer (25 June-17 July). Additional seedings were made at other times in most years. All plots were periodically sampled for dry matter production until maturity or frost. At most samplings, gro wth of soybean [Glycine max L. (Merr.)] was equal to or greater than ( sometimes double) that of the next species. In most situations, hairy vetch (Vicia villosa Roth) also performed well. Field pea (Pisum sativ um L.) or Austrian winter pea [P. sativum L. subsp. sativum var. arven se (L.) Poir.] and fava-bean (Vicia faba L.) grew very rapidly for the first 60 to 90 d after planting. Lespedeza [Kummerowia stipulacea (Ma xim.) Makino] grew relatively well when seeded in early summer, as did tinga pea (Lathyrus tingitanus L.) and cowpea [Vigna unguiculata (L.) Walp. subsp. unguiculata]. Rye (Secale cereale L.) was usually interm ediate, and small-seeded legumes generally exhibited relatively slow g rowth the first 60 d. Results suggest that certain large-seeded, cool- season legumes would produce best for early spring seeding before row crops or summer fallow, whereas some warm-season species would be bett er suited for summer seeding after small grain harvest. Soybean and ha iry etch were well suited for almost all situations in this environmen t.